When an LSI and a liquid crystal board are manufactured, repeat patterns are sometimes formed on an object to be processed (e.g. semiconductor wafer). In such manufacturing of the LSI and the liquid crystal board, when a foreign matter adheres to the surface of the object to be processed or a defect is produced, failure such as, for example, insulation failure of wiring and a short circuit is caused. With recent miniaturization of circuit pattern, it is difficult to distinguish between the pattern formed on the object to be processed (indefective part) and a minute foreign matter or a defect.
Here, the defect is a particle adhered to a sample that is an object to be inspected, a crystal defect COP (Crystal Originated Particle) and a scratch produced by grinding.
With miniaturization of semiconductor devices, the size of a defect and a foreign matter on a minute pattern to be inspected is equal to or smaller than several ten nanometers. Since the size of the defect and the foreign matter to be inspected is small, reflected, diffracted and scattered light from the defect or the foreign matter is very weak and it is difficult to detect it by an optical method. Accordingly, conditions of illumination light for increasing the reflected, diffracted and scattered light from the defect or the foreign matter and conditions of detection thereof are groped. Particularly, in the sub-wavelength structure having semiconductor structure equal to about one tenth of wavelength, a semiconductor has structure birefringence and accordingly the polarization state of the reflected, diffracted and scattered light depends on the semiconductor structure strongly. A wire grid polarizer is a polarization element utilizing the polarization state of the sub-wavelength structure. Attention is paid to the polarization state of the sub-wavelength structure and there has been proposed a method in which the polarization state of incidence and detection is controlled to thereby reduce a signal from a semiconductor pattern and improve the detection sensitivity of defect.
Patent Literature 1 (JP-A-2006-512588 Publication) discloses “a system and a method of inspecting patterned and non-patterned object optically, comprising a step of deciding polarization shift introduced by the pattern and polarization of incident light beam subjected to the polarization shift by the pattern, a step of establishing the polarization state of the light beam in response to the decision and producing incident light beam impinging on the patterned object, a step of filtering reflected beam by polarization in response to the decision, and a step of generating a detection signal in response to detection of the filtered reflected light beam.”